Studies on spectral variation of 2AAQ with solvent properties

Abstract

In order to understand the nature and extent of solute-solvent interactions, the spectral variations of 2-amino-9, 10-anthraquinone (2AAQ) molecule are analyzed by using the linear solvation energy relationship (LSER) concept formulated by Katritzky et al15. The independent contributions of general and specific solute-solvent interactions have been calculated using multiple linear regression analysis method. The strength of the dipolarity and polarizability interaction is more than the specific solute-solvent interactions. Further, the solvation studies in cyclohexane (CHX)-ethyl acetate (EA) and ethyl acetate (EA)-acetonitrile (AN) solvent mixtures indicate that this dye is preferentially solvated by CHX in CHX-EA solvent mixture and EA in EA-AN except in the case of EA20AN80 where solute molecule is preferentially solvated by AN rather than EA. The ground-and excited-state dipole moments of 2AAQ have been estimated by solvatochromic shift method. The change in dipole moment is calculated using the correlation of microscopic solvent polarity parameter with the Stoke's shift. The ground state dipole moments are predicted theoretically in gas phase by Gaussian 03 software using B3LYP/6-31G? level of theory and by semi-empirical method (PM6 ).